In performing water electrolysis in space, it is desirable to separate the process water from the product gases (i.e., H.sub.2 and O.sub.2). Further, it is important not to waste or discharge any of the process water or product gases.
A typical acid membrane electrolyzer has water circulated throuqh the anode (O.sub.2 generation) chamber, as shown in the "electrolysis module" of FIG. 1. A small part of this water transports through the membrane as the electrolysis process is carried out. This water, sometimes referred to as proton water, appears in the hydrogen chamber and is discharged with the hydrogen gas.
In terrestrial applications, the product gases are separated, at pressure, from the process water in gravity separators. The water separated from the hydrogen gas is de-pressurized and a further gravity separation conducted when dissolved hydrogen comes out of solution. In most terrestrial applications, this hydrogen from the ambient pressure separation is simply discarded. This hydrogen side water is then re-injected into the circulating oxygen side water loop.
In zero gravity space applications, water and gas can be separated using various phase preferential, porous materials, including either hydrophilic and/or hydrophobic materials. However, hydrogen gas separated from a second low pressure device would have to be vented. If not vented, pump difficulties could arise.
In any event, the low pressure separated hydrogen would be a parasitic loss. A further difficulty occurs when the space platform prohibits venting.